CA2214145A1 - Sulfur-containing fertilizer and process for production thereof - Google Patents
Sulfur-containing fertilizer and process for production thereof Download PDFInfo
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- CA2214145A1 CA2214145A1 CA002214145A CA2214145A CA2214145A1 CA 2214145 A1 CA2214145 A1 CA 2214145A1 CA 002214145 A CA002214145 A CA 002214145A CA 2214145 A CA2214145 A CA 2214145A CA 2214145 A1 CA2214145 A1 CA 2214145A1
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05B—PHOSPHATIC FERTILISERS
- C05B1/00—Superphosphates, i.e. fertilisers produced by reacting rock or bone phosphates with sulfuric or phosphoric acid in such amounts and concentrations as to yield solid products directly
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G5/00—Fertilisers characterised by their form
- C05G5/10—Solid or semi-solid fertilisers, e.g. powders
- C05G5/12—Granules or flakes
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G5/00—Fertilisers characterised by their form
- C05G5/40—Fertilisers incorporated into a matrix
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Abstract
A particulate sulfur-containing fertilizer comprising a uniform dispersion of sulfur and at least one member selected from the group consisting of ammonium sulfate, ammonium phosphate and mixtures thereof, the sulfur having an average particle size of less than about 100 µm. A process for producing the granulated sulfur-containing fertilizer is described. The process comprises the steps of: (i) providing a first stream comprising ammonia; (ii) providing a second stream comprising at least one member selected from the group consisting of sulfuric acid, phosphoric acid and mixtures thereof; (iii) providing a third stream comprising an aqueous liquid; (iv) mixing the first stream, the second stream and the third stream to form a liquid reaction mixture; (v) feeding the liquid reaction mixture to a mixer; (vi) feeding a fourth stream comprising molten sulfur to the mixer prior to solidification of the reaction mixture; and (vii) solidifying the homogenized melt to produce the granulated sulfur-containing fertilizer.
Description
WO 96/27S71 PcrlcAs6l~7nl2s SULFUR-CONTAINING FERTILIZER AND PROCESS
FOR PRODUCTION THEREOF
TECHNICAL FIELD
The present invention relates to a sulfur-co.. ~ fertilizer and to a )ceSS for production thereof.
BACKGROUND ART
Sulfur and sulfur-cont~ining fertilizers are generally known. Indeed, sulfur is a very important element in the production of crops. Although it has been cl~ified as a secondary el~ment many l-,sea~lt~l~, are of the view that the ul-~ul~lce of sulfur to crop growth and development parallels that of nitrogen, phosphorus and potash. As is known in the art, sulfur acts in a soil system by being oxidized to sulfate which may then be taken up by plants in the soil system.
There are many soil areas in North America where sulfur is inherently low and thus, crop production in these areas is limite<l Further, the ever increasing application of other nutrients and fertilizers, together with generalsoil depletion, has led to incl~a~ g oc-;u"ellce of sulfur-depleted soils.
Generally, in order to attain efficient release of sulfur and illl~ro~ plant growth in a given soil system, it is desirable to present the sulfur in colljul~l;lion with controlled amounts of other elements/nutrients such as nitrogen, phosphorus and the like. For example, in order to attain efficient release of nitrogen, phosphorus and sulfur to plants, a ratio of 10:2:1 is generally desirable. Thus, it is desirable to develop fertilizers which contain two or more elem~ont~/lluL~ in a fixed amount.
Hel~lofole, the art has endeavoured to address the ch~llenge of incorporating two or more elements/nutrients in a single, composite fertilizer material.
For example, United States patent 4,330,319 (E!,exton et al.), the contents of which are hereby incorporated by ler.,l~llce, teaches a urea-sulfur fertilizer and a process for production thereof. Specifically, there is taught CA 0221414~ 1997-08-28 a homogeneous, solid, particulate urea sulfur fertilizer colllplisillg a ullir~
dispersion of finely divided particles of sulfur in a urea matrix, the sulfur particle size being less than about 100 ~m. The fertilizer is produced by cont~çtin~ a molten stream of urea with a molten stream of sulfur, passing the 5 combined streams through a mixing device across which is provided a S~UlC drop of at least about 200 kPa to form a homogenized melt finely divided sulfur dispersed in urea and solidifying the homogenized melt to obtain the urea-sulfur fertilizer. The Examples in Bexton et al. show production of urea-sulfur fertilizers have the following grades: 43.6:0:0:6.3 10and 41.6:0:0:10.5. Bexton et al. teaches a process which clearly requires cont~r-ting a molten stream of urea with a molten stream of sulfur, namely molten streams of the rç~r-t~nt~ which directly form the urea-sulfur fertilizer.Further, the fertilizer taught by Bexton et al. ~Pcess;lS.~r~ the plcscllce of a~ignifir~nt amount of nitrogen.
15It would be desirable to incol~ul~lc sulfate, for example in the form of ammonium sulfate, in a sulfur-co..l;.;,.il-g fertilizer since this would present to the soil system both a short term sulfur dose (i.e. in the form of sulfate) and a long term sulfur dose (i.e. in the form of elemPnt~l sulfur which is eventually oxidized to sulfate). UllrclLul~l~ly, the process desçribed by 20 Bexton et al. is not applicable to incol~olalion of a sulfate such as ~mmonillm sulfate since, once produced, the sulfate can not be plcst;ll~d in a molten form. The plill;i~dl reason for this is that ~mmo~illm sulfate decomposes upon melting.
It would also be desirable to incol~ul~Le phosphate, for example in the 25 form of ammonium phosphate, in a sulfur-cont~ining fertilizer. The main advantage of such a fertilizer would be to combine in a single fertilizer two elements/nutrients normally required for enhz~n~e~l plant growth. Again, the process described by Bexton et al. is not applicable to incorporation of a phosphate such as ammonium phosphate since, once produced, ~mmonium 30 phosphate can not be plcscllLcd in a molten form. The plillci~al reason for this is that ammonium phosphate decomposes upon melting.
CA 02214145 1997-08-i8 .;
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~CJIGAl 9 6 / 0012 9 It would be desirable to have a sulfur-cont~ining fertilizer which incorporates sulphate and/or phosphate. It would be further desirable if the production of such a fertilizer could be readily incorporated into an e,Yisting production process for arnmonium sulphate and/or arnmonium phosphate. It would be further desirable if the production of such a fertilizer could be readily incorporated into existing solidification units (e. g. granulation drums, prilling towers and the like).
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a novel sulfur-cont~inin~ fertilizer which obviates or mitigates at least one of ,~he above-mentioned disadvantages of the prior art.
It is another object of the present invention to provide a novel process for producing a sulfur-cont~ining fertilizer. L
Accordingly, in one of its aspects, the present invention provides a t homogeneous gr imll~ti~d sulfur-cont~ining fertilizer, each granule of the r fertilizer comprising: ; ~ S~ -~r~X Co~
a uniform dispersion of: (i) sulfur particles~ aAd (ii)/l~at least one member selected from the group consisting of ammonium sulfate, ammonium ,---phosphate and mixtures thereof; =c wherein the sulfur particles in the u~lirollll dispersion have an average _~
particle size of about 100 ,um or less when the granule of fertilizer is disintegrated.
Thus, the each granule of the present sulfur-cont~ining fertilizer may be considered to be a fused conglomeration of sulfur particles and at least one of ammonium sulfate and ammonium phosphate. The aramonium phosphate and ammonium sulfate form a granule matrix which contains the element~l sulfur particles. The size of the granule itself can be readily custornized by a person of skill in the art for the needs of the particular user. ~hen a =-granule of the present sulfur-cont~ining fertilizer is broken down (e.g. by application to soil, immersion in water, etc.)"~he granule disintegrates to yield the sulfur portion of the fertilizer as sulfur particles having an average particle ~ . .
WO 96~7~,71 PCTJCA96J~129 size of about 100 ,um or less. Preferably, at least about 50%, more preferably at least about 75%, of the sulfur particles having a particle size of about 100 ~m or less. It will be lln~l.orstc)od by those of skill in the art that the size of each granule of sulfur-co.,~i~i..;..g fertilizer is not particularly restrirte~. As S ~i.ccllsce-l above, size of the granule itself can be readily cusLc~ cd by a person of skill in the art. Preferably, the size of each granule is in the rangeof from about 0.5 mm about 50 mm, more preferably in the range of from about 1 mm to about 10 mm.
In another of its aspects, the present invention provides a process for .10 producing a gr~mll~ted sulfur-cont~ining fertilizer con1prising the steps of:
(i) providing a first stream COlllpli~,illg ammonia;
(ii) providing a second stream complisillg a least one member se-l~cte~, from the group Co~ of s~llfilnr acid, phosphoric acid and llli~lules thereof;
(iii) providing a third stream coul~ iug an aqueous liquid;
(iv) mixing the first stream, the second stream and the third stream to form a liquid reaction mixture;
(v) feeding the liquid reaction ~ Lulc to a mixer;
(vi) feeding a fourth stream Colll~ illg molten sulfur to the mixer;
(vii) m~int~ining a ~ u,c drop across the mixer of at least about 200 kPa to form a homogenized melt of sulfur-cont~inin~ fertilizer; and (viii) solidifying the homogeni7~o-1 melt to produce the gr~nlll~te~
sulfur-cont~ining fertilizer.
In yet another of its aspects, the present invention provides a process 25 for producing a gr~mll~t~od sulfur-co~i1ii,.g fertilizer Colll~lisi,lg the steps of:
(i) providing a first stream comprising ammonia;
(ii) providing a second stream c~,ll,pli~,hlg a least one member selPcte~l from the group u n.ci.cting of sulfuric acid, phosphoric acid and ~ lulcS thereof;
(iii) providing a third stream comprising an aqueous liquid;
(iv) mixing the first stream, the second stream and the third stream to form a liquid reaction llli~LIUl~;;
(v) feeding the liquid reaction mixture to a mixer;
(vi) feeding a fourth stream comprising molten sulfur to the mixer prior to solitii~lr~tion of the reaction llli~lUl~,; and (vii) solidifying the homogenized melt to produce the gr~mll~t~-sulfur-cont~inin~ fertilizer.
T~hus, it has been discovered, inter alia, that a sulfur-co~t~inin~
fertilizer which incol~o~at~s slllI h~t~ and/or phosphate can be produced if el~ nt~l sulfur, in molten form, is incorporated into the reaction to produce ammonium sulfate and/or ammonium phosphate. In other words, it has been discovered that such a sulfur-cont~ining fertilizer can be produced if the re~ t~nts in the ammonium sulfate and/or ammonium phosphate processes are col.~;~d with elP~n~nt~l sulfur prior to soli~lifi~ ~ti~ n of the ammonium sulfate and/or ammonium pho~ dle (i.e. prior to soli~1ifi~tion of the reaction llli~ul~ formed by mixing and reacting the first stream, second stream and third stream referred to hereinabove). Specifically, as ~ ed above, once the ammonium sulfate and/or ammonium phosphate have been solidified it is not possible to inco.~o-~le molten sulfur ~ . ilh in a ~llliro"" and homo~ euus lll~t;l. The ~,h~ al reason for this is that allllllOlliUlll sulfate and ammonium phosphate will subst~nti~lly decompose on m~lting.
As used herein, the term "sulfur-coll~ fertilizer" is int~ntl~cl to mean a gr~mll~t~l fertilizer which com~,ises a conglomeration of elemental sulfur particles. In the context of an embodiment of the present invention, the sulfur-cont~ining fertilizer also contains at least one lllt;lllbel selected from the group con~i~tin~ of ammonium sulfate, ammonium phosphate and llli~lul~,s thereof. Further, as used herein, the term ammonium phosphate is int~n~ie to have a broad ml-~nin~ and includes one or more of the following:
NH4H2PO4, (NH4)2HPO4 and (NH4)3PO4. Still further, as used herein, the term ammonium sulfate is intenl1e~ to have a broad m~ning and includes one or more of the following (NH4)2SO4 and NH4HS04, the former being the predo,llillal,l form of ammonium sulfate used in the fertilizer industry.
Preferably, the present sulfur-cont~ining fertilizer co---~-ises from about 1% to about 80%, more preferably from about 20% to about 60%, by weight element~l sulfur. As is known in the art a practical upper limit to the amount of sulfur which is used in a fertilizer is reached when the fertilizer becomes fl~mm~hle (i.e. explosive) and thus, becomes dangeluus to handle and use. The bulk of the l~ g portion (subject to p~csellce of trace 5 elemPntc) of the fertilizer is made up of ~mmnnil-m phosphate and amrnonium sulfate. The proportion of these components is not particularly restricted and is usually ~lict~ted by the market need for the product. .~--ffiriPnt ammonium sulfate should be used to facilitate keeping the cl~ ;.l sulfur as distinct particles within the granule matrix.
The present sulfur-co,l~ illg fertilizer may further comprise at least one trace elemPnt sPl~octe~ from the group concicting of zinc, m~"P~iu.ll, m~ Pse, iron, copper, calcium and ~ LLurcs thereof, whereill the aggregate amount of trace el~mPnt is less than about 5% by weight of the fertilizer. The source of these trace ehPmPntc or miclulluLliclll~ is not particularly le;,LIicLed.
Preferably, the trace elemPnt~ are colll~lised in a waste effluent from an industrial process. More preferably, the trace elements may also act as gr~n~ tion agents for the sulfur-cont~inin~ fertilizer. Most preferably, if used, the trace elements are present as a granulation agent in the forrn of a stripped zinc electrolyte. If a stripped zinc electrolyte is used as a gr~n~ til~n agent (di~cllsse(l in more detail h~,lcinl)elow) to produce the present sulfur-cont~ining fertilizer, it is preferred that the sulfur-cont~ining fertilizer fur~er cuul~,ises up to about 1.5%, more preferably from about 0.4% to about 1.3%, by weight zinc, from about 0.01% to about 0.2%, more preferably from about 0.07% to about 0.16%, by weight m~gn~sillm and from about 0.01% to about 0.1%, preferably from about 0.04% to about 0.09%, by weight " IA l~g~ sse.
BRIEF DESCRIPTION OF THE DRAWING
Embo~limf~nt~ of the present invention will be described with rcrcl~nce to the accolll~lying drawing of Figure in which there is ill~ cl a srh~ ic of a plant and process for production of a sulfur-cont~ining fertilizer in acco,.l~lce with an embodiment of the present invention.
,~
Pl~ AI 96/oO129 ~.~
,~ -7-BEST MODE FOR CARRYING OUT THE INVENTION
With reference to the Figure, there is illustrated a plant 10 for production of a sulfur-cont~ining fertilizer.
Plant 10 comprises a jacketed mixer 15. A feed line 20 is conn~ctefl 5 at one end to mixer 15 and at the other end to a molten sulfur holding tank 25. The nature of holding tank 25 is not particularly restricted nor is the method of providing the molten sulfur, both of which are within the purview of a person skilled in the art. See, for example United States patent 4,286,966 (Kirby et al.), the contents of which are hereby incorporated by . ~_~
10 reference. Preferably, line 20 and holding tank 25 are designed and operated to nn~int~in the molten sulfur at a temperature in the range of from about~~ l3 ~
to about~~C, more preferably from about 135~ to about ~C.
The precise nature of mixer 15 is not particularly restricted and is preferably one which will be able to provide particle sizes of discrete sulfur 15 in the sulfur-cont~ining fertilizer having an average particle size of less than about 100 ,um. Preferably, the mixing device should be capable of effecting a pressure drop across itself of at least about 200 kPa, more preferably at least about 350 kPa, even more preferably at least about 500 kPa and may be as high as 1500 kPa or more. Persons skilled in the art will be able to reconcile 20 the degree of pressure drop effected by a particular mixer (the higher the pressure drop, the higher the degree of homogenization obtained) with the energy required to operated the mixer in such a manner (more energy is required to attain a higher pressure drop which increases the overall cost of the process). See, for example, United States patent 4,330,319 (Bexton et 25 al.), the contents of which are hereby incorporated by reference. The mixing device may be a homogenizer or a static mixer. Examples of suitable mixing devices include a BlendrixTM Motionless Mixer or a RossTM Motionless Mixer.
If, at the point of molten sulfur injection, there is suf~lcient turbulence in the system caused by the neutralizing reaction involved in the production 30 of the ammonium sulfate or ammonium phosphate (i.e. the molten elemental sulfur is added just dowl~Lleal., of the location in which the neutralizing reaction is occurring), the relatively high pressure drop referred to above may . ; ~GTI.~AJ 9 6 / 00 1 2 9 _~_ not be required to achieve dispersion of the sulfur into particles which are sufficiently small in size.
The inlet of mixer 15 is adapted to include a premixer 30 which is equipped with a quill 35. Quill 35 is a tubular pipe having an inlet 40 and an S outlet 45. The portion of quill 35 disposed in premixer 30 comprises a plurality of jets 50. It will be appreciated by those of skill in the art that aseries of perforations (not shown) can be used in place of jets 50.
A line 55 is connected at one end to inlet 40 of quill 35 and at the other end to a scrubber liquor holding tank 60. ~he nature of the scrubber 10 liquor housed in holding tank 60 will be described hereinbelow.
A line 65 is conn~oct~ at one end to line 55 and at the other end to an arnmonia holding tank 70 or any other suitable source of ammonia (not shown). A line 75 is corLnected at one end to line 55 and at the other end to a granulation agent holding tank 80. The granulation agent housed in holding 15 tank 80 is not particularly restricted. The incorporation of a gr~mll~rion agent generally is known in the art. See, for exarnple Australian patent 492,758 (Golding), the contents of which are hereby incorporated by reference.
Preferably, the gr~mll~ti~-n agent is selected from the group consisting of zinc sulphate, ammonium phosphate, ~ mimlm sulfate and mixtures 20 thereof. A particularly ~iefell~d form of granulation agent is a stripped zinc electrolyte as described in United States patent 5,383,951 (Cross et al.), the contents of which are hereby incorporated by reference. A pl~relled stripped zinc electrolyte comprises from about 10 to abo~t 30 g/L zinc, up to about 10 ~a,. o ~ eS
g/L magnesium, up to about 10 g/L~an~ up to about 250 g/L sulfuric acid.
25 A more L~i~Çelled stripped zinc electrolyte comprises from about 20 to about 25 g/L zinc, from about 2 to about 4 g/L magnesium, from 1 about to about ~10 g/L m~ng~nese and from about 190 to about 200 g/L sulfuric acid.
~ A line 85 is conn~octed at one end to premixer 30 and at the other end to an acid holding tank 90. If a sulfur-ammonium sulfate fertilizer is to be 30 produced, acid holding tank 90 contains sulfuric acid. If a sulfur-ammonium phosphate fertilizer is to be produced, acid holding tank 90 contains phosphoric acid. If a final product cont~inin~ both ammonium phosphate and CA 0221414~ 1997-08-28 W O96127S71 PCT/CAg6100129 arnmonium sulfate is desired, acid holding tank 90 contains sulfuric acid and phnsphnric acid. ~ltern~tively, acid holding tank 90 may be divided into two independent tanks (not shown), each independent tank cont~ining one of the acids and further comprising a line to feed each acid to premixer 30.
Mixer 15 is provided with an outlet 95 to which is conn~cte~ a thermost~ti~lly heated line 100. Line 100 is cnnn~cte~l to a granulation unit 110. Gram-l~tion unit 110 is not particularly le.,LIicL~d and suitable units areknown in the art. See, for example, United States patent 4,234,318 (~iggin~
et al.), the contents of which are hereby inco"~o.dted by .ere.~;-.ce.
From granulationunit 110 a stream comprising on-specificationproduct exits via a line 125 and is fed to dryer, screening and p~ ging units (not shown). Another stream colll~lisillg under-sized, off-specification product, also known as "fines" together with air used in granulation unit 110, exits granulation unit 110 via a line 145 and is fed to a scrubber unit 150. Aqueous scrubber liquor formed in scrubber unit 150 is fed to scruWer liquor holding tank 60 via a line 155. Cleaned air e,~ s from scrubber unit 150 via line 115 and is further treated and/or vented to the atmosphere.
The present sulfur-cont~ining fertilizer may be produced in the following manner. A suitable valve (not shown) in line 55 2~ cent holding tank 60 is opened and aqueous scrubber liquor begins to flow in line 55.
Suitable valves (not shown) in lines 65 and 75, respectively, are opened to permit a flow of ammonia and gramll~ti~n agent, ~ peclivt:ly. Preferably, flow in lines 55 and 65 is ~rei,~uli~ed, more preferably in the range of from about 200 to about 300 psi (about 1380 to about 2070 kPa), most preferably in the range of from about 250 to about 300 psi (about 1725 to about 2070 kPa).
Con~;u~ ly, a valve (not shown) in line 85 is opened to permit a flow of acid (sulfuric acid or phosphoric acid) to premixer 30. Preferably, the flow in line 85 is pressurized, more preferably in the range of from about 200 to about 300 psi (about 1380 to about 2070 kPa), most preferably in the range of from about 250 to about 300 psi (about 1725 to about 2070 kPa).
CA 0221414~ 1997-08-28 Thus, the contt~nt~ of line 55 at inlet 40 of quill 35 comprise ammonia, scrubber liquor and granulation agent. The aqueous liquid is then fed to quill 35 where it exits Lllclcrlvnl via jets 50 into the mass of acid present in premixer 30 to form an c~olhellllic reaction mi~lulc. As will be a~alclll to 5those of skill in the art, these flows may be reversed such that the aqueous liquid is fed in and around quill 35, and the acid (or acids) is added through quill 35. This alternative configuration has the added advantage of minimi7.in~
corrosion of quill 35 and jets 50.
The exother~nic reaction mixture is then fed from premixer 30 to mixer 15. Con;ullclllly, a valve (not shown) in line 20 is opened to permit a flow of molten sulfur to enter mixer 15. Preferably, the flow in line 20 is s~ul.~.ed, more preferably in the range of from about 200 to about 300 psi (about 1380 to about 2070 kPa), most preferably in the range of from about 250 to about 300 psi (about 1725 to about 2070 kPa). The exoth~rmir reaction mixture and molten sulfur stream are homogeni7.od in mixer 15 to produce a multi-component slurry. As t~ c--~se-l above, mixer 15 is conventional and the operation thereof to provide a pressure drop of at least about 200 kPa is within the purview of a person skilled in the art.
The multi-component slurry exits mixer 15 via outlet 95 and enters line 100. As tli~clls~ed above, a prcs~ulc drop is created across mixer 15.
Preferably, this results in the pressure of the multi-component slurry exiting mixer 15 being in the range of from about 10 to about 50 psi (about 70 to about 350 kPa), more preferably from about 10 to about 30 psi (about 70 to about 210 kPa).
Preferably, line 100 is m~int~in~d at a temperature of at least about 120~C, more preferably in the range of from about 130~ to about 170~C.
This may be accomplished by m~int~ining a back-plcs~ule in the sprayer (not shown) in granulation unit 110 sufficient to avoid steam flash of the multi-component slurry which would cause cooling of the slurry to a temperature below that which is desired to achieve good granulation.
Preferably, within about 10 seconds of exiting mixer 15, the multi-component slurry enters granulation unit 110 wherein it is solidified and wo 96127571 PCr/CA96100129 gr~mll~t~l. As ~ cllesed hereinabove, gr~mll~ti~ n unit 110 is conventional and the operation thereof to produce a gr~mll~te~ product is within the purview of a person skill in the art.
As rli~cll~d above, on-specification product is removed from the S effluent of granulation unit 110 by any conventional technique such as screening and, ~lc..,arlel, is conveyed drying, screening and pae~ging units (not shown). The air from granulation unit 110 contains fine dust particles and this stream is passed through scrubber unit 150. Aqueous scrubber liquor formed in scrubber unit 150 is fed to scrubber liquor holding tank 60 via a 10 line lSS and cleaned air e~ ;s from scrubber unit 150 via line llS.
As is known in the art, the amounts of ammonia, acid, sulfur and aqueous stream may be regulated according to the ~lo~cllies desired in the product. For example, the acid typically is used in an amount which regulates the rate of production of the sulfur-cont~ining fertilizer. The amount of 15 ammonia used is approximately stoichiometric to provide a sulfur-co~ g fertilizer having a pH of from about 4 to about 7.5. The aqueous stream (e.g.
scrubber liquor) is used in an amount to ensure s~ti~f~ctory soli~lifir~ti~ n ofthe homogenized melt, and also to help to control the mixer L~ elaLule. The molten sulfur is used in amount which will result in t'ne desired sulfur level in the fertilizer product.
While the present invention has been described in detail with l~Çelcl~ce to a single illustrated embodiment, it will of course be readily understood thata number of modifications to the illu7LIated embodiment will be ~ar~lll to those of skill in the art.
For example, granulation unit 110 may be modified or substituted with a dirr~lenl soli~lifir~tion unit. Another pl~f~ d solillifir~tic~n unit is a prilling tower, for example, such as those disclosed in United States patents 4,153,431 (Higgins) and 4,389,356 (Higgins), the contents of each of which are hereby incorporated by .-,rerellce. Other ~ rt:lled soli~lifir~tion units include an inrlin-od rotating pan and a flni-li7tod bed.
Another motliflr~tinn contemplated herein is elimin~tion from the illustrated embodiment of the need for a gr~nlll~tion agent. As is known in CA 0221414~ 1997-08-28 the art, granulation agents are desirable specifically for in ammonium sulfate production since, in granulation processes, this compound a&eres to itself relatively poorly. In the present process, while use of a gr~n~ tion agent is ~l~,r~lled is believed to be not required since the molten sulfur added during S the present process will serve to promote the needed a&esion. -Yet another modification contemplated herein is mo~lifi-~tion of the illustrated embodiment to utilize the granulation agent at any point in the process up to the soli-lifi~tion unit. In other words, it is contemplated that the granulation agent can be injected, for example, adjacent granulation unit 10 110 after mixer 15.
Yet another motlific~tion cont~mplated herein is elimin~tion from the illustrated embodiment of the need for a sclubbel liquor. Specif1cally, the use of a scrubber liquor is a col~venient way to introduce water into the reaction system. As is known in the art, water is needed to facilitate mixing of the 15 re~ct~nt~, and h~nllling and gr~n~ tion of the reaction product. In the present process, it is convenient, and thus ~l~rell~d, to use scrubber liquor as the water source since scluWillg and production of scrubber liquor is collv~llLionalin the art. However, it should be clearly recognized ~hat the source of water can be other than scrubber liquor. For example, the source of water could be 20 a dilute stream of acid. ~lt~rn~tively, the source of water could be the stripped zinc electrolyte, if used. Of course, persons skilled in the art will recognize that the source of water can be spread over two or more reactant streams to the process (e.g. portion in the form of relatively dilute acid and portion in the form of stripped zinc electrolyte).
Yet another mo~lifir~tion contemplated herein is modification to the illustrated embodiment of the combination of mixer 15 and premixer 30.
Specifically, it is contemplated that these elements need not be integral and can be remote from one another.
Yet another modifir~tion contemplated herein is elimin~tlod of j~k~oted mixer 15 shown in the illustrated emborlim~nt In this modification, the output of premixer 30 would be conn~qct~ directly to line 100 and line 20 from holding tank 25 would be conn~cte-l via a con\~llLional valve junction to W O 96/27S71 PCTICAg6100129 line 100. This mc~1ifir~tion eli...i..~s the need for j~cl~te(l mixer 15 and allows for in-line mixing of the molten sulfur with the reaction ~ n~
from premixer 30 (i.e. line 100 provides in situ mixing of the molten sulfur and the reaction Il~xlule). Such a design mo-lifir~tion was used in the J 5 Example described hereinbelow.
Further modifications will be appalelll to those of skill in the art with this specification in hand, which modifications do not depart from the spirit of the present invention.
Embo-limPnt~ of the present invention will be described with lcrclcllce to the following Example which should not be used to limit the scope of the mvenhon.
EXAMPLE
In this Example, a fertilizer cont~ining sulfur and ammonium sulfate was produced in a pilot plant.
The design of t'ne pilot plant reactor was similar to that disclosed in the Figure referred to above, modified in the following lllam~el. The flow into quill 35 and premixer 30 was leve.~,ed such that ammonia and water were fed to premixer 30 to ~ull~und quill 35 and sulfuric acid was fed into quill 35.
Further, mixer 15 was elimin~t~ and the output from premixer 30 was fed dhcclly to a heated line. The molten sulfur was injected into the heated line via an injection nozzle to provide in-line mixing of the molten sulfur stream with sulfuric acid/water/ammonia stream.
Ammonia vapour was fed from ammonia bottles via a plC~7.7UlC
regulator set at 70 psig and through a mass flowmeter/controller. Sulfur was fed from a steam jacketed, nitrogen plcs~,uli~ed tank at 90 psig via a steam j~ck~tecl line and steam j~rk~te~l rotameter to the injection nozzle.
Supplementary electric heaters were used to heat the sulfur line, as n~cess~y.
Large lab size gear pumps were used to pump sulfuric acid (82 psig) and water (80 psig) through their .e~,l,e.;li~e lines to the reactor (i.e. water to premixer and sulfuric acid to quill).
W O96/27S71 PCT/CAg6/00129 The reactor was opelaled for 90 ...i..~ s at 166~C. Spray slurry samples were periodically taken and found to contain 47% elem~ont~l sulfur.
Gr~mll~t~o~l samples from the gr~mll~tinn unit co~ ed 1040% sulfur, as the particles in the granulator were slowly changed from the fine ammonium 5 sulfate which was used as the initial dry feed for the granulator.
The gramll~te~l samples were subjected to a sulfur size distribution analysis by conventional wet screen analysis. The particle size distribution of the gr~mll~te~l product may be found in Table 1.
MeshParticle Size (~m) Fraction (wt. %) +48 297 1.9 +65 208 4.3 + 100 150 10.3 +200 75 27 +325 45 81 Thus, these test results illnstrat~ that approximately 75% of sulfur particles in the fertilizer had a particle size of less than 75 ~bm.
FOR PRODUCTION THEREOF
TECHNICAL FIELD
The present invention relates to a sulfur-co.. ~ fertilizer and to a )ceSS for production thereof.
BACKGROUND ART
Sulfur and sulfur-cont~ining fertilizers are generally known. Indeed, sulfur is a very important element in the production of crops. Although it has been cl~ified as a secondary el~ment many l-,sea~lt~l~, are of the view that the ul-~ul~lce of sulfur to crop growth and development parallels that of nitrogen, phosphorus and potash. As is known in the art, sulfur acts in a soil system by being oxidized to sulfate which may then be taken up by plants in the soil system.
There are many soil areas in North America where sulfur is inherently low and thus, crop production in these areas is limite<l Further, the ever increasing application of other nutrients and fertilizers, together with generalsoil depletion, has led to incl~a~ g oc-;u"ellce of sulfur-depleted soils.
Generally, in order to attain efficient release of sulfur and illl~ro~ plant growth in a given soil system, it is desirable to present the sulfur in colljul~l;lion with controlled amounts of other elements/nutrients such as nitrogen, phosphorus and the like. For example, in order to attain efficient release of nitrogen, phosphorus and sulfur to plants, a ratio of 10:2:1 is generally desirable. Thus, it is desirable to develop fertilizers which contain two or more elem~ont~/lluL~ in a fixed amount.
Hel~lofole, the art has endeavoured to address the ch~llenge of incorporating two or more elements/nutrients in a single, composite fertilizer material.
For example, United States patent 4,330,319 (E!,exton et al.), the contents of which are hereby incorporated by ler.,l~llce, teaches a urea-sulfur fertilizer and a process for production thereof. Specifically, there is taught CA 0221414~ 1997-08-28 a homogeneous, solid, particulate urea sulfur fertilizer colllplisillg a ullir~
dispersion of finely divided particles of sulfur in a urea matrix, the sulfur particle size being less than about 100 ~m. The fertilizer is produced by cont~çtin~ a molten stream of urea with a molten stream of sulfur, passing the 5 combined streams through a mixing device across which is provided a S~UlC drop of at least about 200 kPa to form a homogenized melt finely divided sulfur dispersed in urea and solidifying the homogenized melt to obtain the urea-sulfur fertilizer. The Examples in Bexton et al. show production of urea-sulfur fertilizers have the following grades: 43.6:0:0:6.3 10and 41.6:0:0:10.5. Bexton et al. teaches a process which clearly requires cont~r-ting a molten stream of urea with a molten stream of sulfur, namely molten streams of the rç~r-t~nt~ which directly form the urea-sulfur fertilizer.Further, the fertilizer taught by Bexton et al. ~Pcess;lS.~r~ the plcscllce of a~ignifir~nt amount of nitrogen.
15It would be desirable to incol~ul~lc sulfate, for example in the form of ammonium sulfate, in a sulfur-co..l;.;,.il-g fertilizer since this would present to the soil system both a short term sulfur dose (i.e. in the form of sulfate) and a long term sulfur dose (i.e. in the form of elemPnt~l sulfur which is eventually oxidized to sulfate). UllrclLul~l~ly, the process desçribed by 20 Bexton et al. is not applicable to incol~olalion of a sulfate such as ~mmonillm sulfate since, once produced, the sulfate can not be plcst;ll~d in a molten form. The plill;i~dl reason for this is that ~mmo~illm sulfate decomposes upon melting.
It would also be desirable to incol~ul~Le phosphate, for example in the 25 form of ammonium phosphate, in a sulfur-cont~ining fertilizer. The main advantage of such a fertilizer would be to combine in a single fertilizer two elements/nutrients normally required for enhz~n~e~l plant growth. Again, the process described by Bexton et al. is not applicable to incorporation of a phosphate such as ammonium phosphate since, once produced, ~mmonium 30 phosphate can not be plcscllLcd in a molten form. The plillci~al reason for this is that ammonium phosphate decomposes upon melting.
CA 02214145 1997-08-i8 .;
.
~CJIGAl 9 6 / 0012 9 It would be desirable to have a sulfur-cont~ining fertilizer which incorporates sulphate and/or phosphate. It would be further desirable if the production of such a fertilizer could be readily incorporated into an e,Yisting production process for arnmonium sulphate and/or arnmonium phosphate. It would be further desirable if the production of such a fertilizer could be readily incorporated into existing solidification units (e. g. granulation drums, prilling towers and the like).
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a novel sulfur-cont~inin~ fertilizer which obviates or mitigates at least one of ,~he above-mentioned disadvantages of the prior art.
It is another object of the present invention to provide a novel process for producing a sulfur-cont~ining fertilizer. L
Accordingly, in one of its aspects, the present invention provides a t homogeneous gr imll~ti~d sulfur-cont~ining fertilizer, each granule of the r fertilizer comprising: ; ~ S~ -~r~X Co~
a uniform dispersion of: (i) sulfur particles~ aAd (ii)/l~at least one member selected from the group consisting of ammonium sulfate, ammonium ,---phosphate and mixtures thereof; =c wherein the sulfur particles in the u~lirollll dispersion have an average _~
particle size of about 100 ,um or less when the granule of fertilizer is disintegrated.
Thus, the each granule of the present sulfur-cont~ining fertilizer may be considered to be a fused conglomeration of sulfur particles and at least one of ammonium sulfate and ammonium phosphate. The aramonium phosphate and ammonium sulfate form a granule matrix which contains the element~l sulfur particles. The size of the granule itself can be readily custornized by a person of skill in the art for the needs of the particular user. ~hen a =-granule of the present sulfur-cont~ining fertilizer is broken down (e.g. by application to soil, immersion in water, etc.)"~he granule disintegrates to yield the sulfur portion of the fertilizer as sulfur particles having an average particle ~ . .
WO 96~7~,71 PCTJCA96J~129 size of about 100 ,um or less. Preferably, at least about 50%, more preferably at least about 75%, of the sulfur particles having a particle size of about 100 ~m or less. It will be lln~l.orstc)od by those of skill in the art that the size of each granule of sulfur-co.,~i~i..;..g fertilizer is not particularly restrirte~. As S ~i.ccllsce-l above, size of the granule itself can be readily cusLc~ cd by a person of skill in the art. Preferably, the size of each granule is in the rangeof from about 0.5 mm about 50 mm, more preferably in the range of from about 1 mm to about 10 mm.
In another of its aspects, the present invention provides a process for .10 producing a gr~mll~ted sulfur-cont~ining fertilizer con1prising the steps of:
(i) providing a first stream COlllpli~,illg ammonia;
(ii) providing a second stream complisillg a least one member se-l~cte~, from the group Co~ of s~llfilnr acid, phosphoric acid and llli~lules thereof;
(iii) providing a third stream coul~ iug an aqueous liquid;
(iv) mixing the first stream, the second stream and the third stream to form a liquid reaction mixture;
(v) feeding the liquid reaction ~ Lulc to a mixer;
(vi) feeding a fourth stream Colll~ illg molten sulfur to the mixer;
(vii) m~int~ining a ~ u,c drop across the mixer of at least about 200 kPa to form a homogenized melt of sulfur-cont~inin~ fertilizer; and (viii) solidifying the homogeni7~o-1 melt to produce the gr~nlll~te~
sulfur-cont~ining fertilizer.
In yet another of its aspects, the present invention provides a process 25 for producing a gr~mll~t~od sulfur-co~i1ii,.g fertilizer Colll~lisi,lg the steps of:
(i) providing a first stream comprising ammonia;
(ii) providing a second stream c~,ll,pli~,hlg a least one member selPcte~l from the group u n.ci.cting of sulfuric acid, phosphoric acid and ~ lulcS thereof;
(iii) providing a third stream comprising an aqueous liquid;
(iv) mixing the first stream, the second stream and the third stream to form a liquid reaction llli~LIUl~;;
(v) feeding the liquid reaction mixture to a mixer;
(vi) feeding a fourth stream comprising molten sulfur to the mixer prior to solitii~lr~tion of the reaction llli~lUl~,; and (vii) solidifying the homogenized melt to produce the gr~mll~t~-sulfur-cont~inin~ fertilizer.
T~hus, it has been discovered, inter alia, that a sulfur-co~t~inin~
fertilizer which incol~o~at~s slllI h~t~ and/or phosphate can be produced if el~ nt~l sulfur, in molten form, is incorporated into the reaction to produce ammonium sulfate and/or ammonium phosphate. In other words, it has been discovered that such a sulfur-cont~ining fertilizer can be produced if the re~ t~nts in the ammonium sulfate and/or ammonium phosphate processes are col.~;~d with elP~n~nt~l sulfur prior to soli~lifi~ ~ti~ n of the ammonium sulfate and/or ammonium pho~ dle (i.e. prior to soli~1ifi~tion of the reaction llli~ul~ formed by mixing and reacting the first stream, second stream and third stream referred to hereinabove). Specifically, as ~ ed above, once the ammonium sulfate and/or ammonium phosphate have been solidified it is not possible to inco.~o-~le molten sulfur ~ . ilh in a ~llliro"" and homo~ euus lll~t;l. The ~,h~ al reason for this is that allllllOlliUlll sulfate and ammonium phosphate will subst~nti~lly decompose on m~lting.
As used herein, the term "sulfur-coll~ fertilizer" is int~ntl~cl to mean a gr~mll~t~l fertilizer which com~,ises a conglomeration of elemental sulfur particles. In the context of an embodiment of the present invention, the sulfur-cont~ining fertilizer also contains at least one lllt;lllbel selected from the group con~i~tin~ of ammonium sulfate, ammonium phosphate and llli~lul~,s thereof. Further, as used herein, the term ammonium phosphate is int~n~ie to have a broad ml-~nin~ and includes one or more of the following:
NH4H2PO4, (NH4)2HPO4 and (NH4)3PO4. Still further, as used herein, the term ammonium sulfate is intenl1e~ to have a broad m~ning and includes one or more of the following (NH4)2SO4 and NH4HS04, the former being the predo,llillal,l form of ammonium sulfate used in the fertilizer industry.
Preferably, the present sulfur-cont~ining fertilizer co---~-ises from about 1% to about 80%, more preferably from about 20% to about 60%, by weight element~l sulfur. As is known in the art a practical upper limit to the amount of sulfur which is used in a fertilizer is reached when the fertilizer becomes fl~mm~hle (i.e. explosive) and thus, becomes dangeluus to handle and use. The bulk of the l~ g portion (subject to p~csellce of trace 5 elemPntc) of the fertilizer is made up of ~mmnnil-m phosphate and amrnonium sulfate. The proportion of these components is not particularly restricted and is usually ~lict~ted by the market need for the product. .~--ffiriPnt ammonium sulfate should be used to facilitate keeping the cl~ ;.l sulfur as distinct particles within the granule matrix.
The present sulfur-co,l~ illg fertilizer may further comprise at least one trace elemPnt sPl~octe~ from the group concicting of zinc, m~"P~iu.ll, m~ Pse, iron, copper, calcium and ~ LLurcs thereof, whereill the aggregate amount of trace el~mPnt is less than about 5% by weight of the fertilizer. The source of these trace ehPmPntc or miclulluLliclll~ is not particularly le;,LIicLed.
Preferably, the trace elemPnt~ are colll~lised in a waste effluent from an industrial process. More preferably, the trace elements may also act as gr~n~ tion agents for the sulfur-cont~inin~ fertilizer. Most preferably, if used, the trace elements are present as a granulation agent in the forrn of a stripped zinc electrolyte. If a stripped zinc electrolyte is used as a gr~n~ til~n agent (di~cllsse(l in more detail h~,lcinl)elow) to produce the present sulfur-cont~ining fertilizer, it is preferred that the sulfur-cont~ining fertilizer fur~er cuul~,ises up to about 1.5%, more preferably from about 0.4% to about 1.3%, by weight zinc, from about 0.01% to about 0.2%, more preferably from about 0.07% to about 0.16%, by weight m~gn~sillm and from about 0.01% to about 0.1%, preferably from about 0.04% to about 0.09%, by weight " IA l~g~ sse.
BRIEF DESCRIPTION OF THE DRAWING
Embo~limf~nt~ of the present invention will be described with rcrcl~nce to the accolll~lying drawing of Figure in which there is ill~ cl a srh~ ic of a plant and process for production of a sulfur-cont~ining fertilizer in acco,.l~lce with an embodiment of the present invention.
,~
Pl~ AI 96/oO129 ~.~
,~ -7-BEST MODE FOR CARRYING OUT THE INVENTION
With reference to the Figure, there is illustrated a plant 10 for production of a sulfur-cont~ining fertilizer.
Plant 10 comprises a jacketed mixer 15. A feed line 20 is conn~ctefl 5 at one end to mixer 15 and at the other end to a molten sulfur holding tank 25. The nature of holding tank 25 is not particularly restricted nor is the method of providing the molten sulfur, both of which are within the purview of a person skilled in the art. See, for example United States patent 4,286,966 (Kirby et al.), the contents of which are hereby incorporated by . ~_~
10 reference. Preferably, line 20 and holding tank 25 are designed and operated to nn~int~in the molten sulfur at a temperature in the range of from about~~ l3 ~
to about~~C, more preferably from about 135~ to about ~C.
The precise nature of mixer 15 is not particularly restricted and is preferably one which will be able to provide particle sizes of discrete sulfur 15 in the sulfur-cont~ining fertilizer having an average particle size of less than about 100 ,um. Preferably, the mixing device should be capable of effecting a pressure drop across itself of at least about 200 kPa, more preferably at least about 350 kPa, even more preferably at least about 500 kPa and may be as high as 1500 kPa or more. Persons skilled in the art will be able to reconcile 20 the degree of pressure drop effected by a particular mixer (the higher the pressure drop, the higher the degree of homogenization obtained) with the energy required to operated the mixer in such a manner (more energy is required to attain a higher pressure drop which increases the overall cost of the process). See, for example, United States patent 4,330,319 (Bexton et 25 al.), the contents of which are hereby incorporated by reference. The mixing device may be a homogenizer or a static mixer. Examples of suitable mixing devices include a BlendrixTM Motionless Mixer or a RossTM Motionless Mixer.
If, at the point of molten sulfur injection, there is suf~lcient turbulence in the system caused by the neutralizing reaction involved in the production 30 of the ammonium sulfate or ammonium phosphate (i.e. the molten elemental sulfur is added just dowl~Lleal., of the location in which the neutralizing reaction is occurring), the relatively high pressure drop referred to above may . ; ~GTI.~AJ 9 6 / 00 1 2 9 _~_ not be required to achieve dispersion of the sulfur into particles which are sufficiently small in size.
The inlet of mixer 15 is adapted to include a premixer 30 which is equipped with a quill 35. Quill 35 is a tubular pipe having an inlet 40 and an S outlet 45. The portion of quill 35 disposed in premixer 30 comprises a plurality of jets 50. It will be appreciated by those of skill in the art that aseries of perforations (not shown) can be used in place of jets 50.
A line 55 is connected at one end to inlet 40 of quill 35 and at the other end to a scrubber liquor holding tank 60. ~he nature of the scrubber 10 liquor housed in holding tank 60 will be described hereinbelow.
A line 65 is conn~oct~ at one end to line 55 and at the other end to an arnmonia holding tank 70 or any other suitable source of ammonia (not shown). A line 75 is corLnected at one end to line 55 and at the other end to a granulation agent holding tank 80. The granulation agent housed in holding 15 tank 80 is not particularly restricted. The incorporation of a gr~mll~rion agent generally is known in the art. See, for exarnple Australian patent 492,758 (Golding), the contents of which are hereby incorporated by reference.
Preferably, the gr~mll~ti~-n agent is selected from the group consisting of zinc sulphate, ammonium phosphate, ~ mimlm sulfate and mixtures 20 thereof. A particularly ~iefell~d form of granulation agent is a stripped zinc electrolyte as described in United States patent 5,383,951 (Cross et al.), the contents of which are hereby incorporated by reference. A pl~relled stripped zinc electrolyte comprises from about 10 to abo~t 30 g/L zinc, up to about 10 ~a,. o ~ eS
g/L magnesium, up to about 10 g/L~an~ up to about 250 g/L sulfuric acid.
25 A more L~i~Çelled stripped zinc electrolyte comprises from about 20 to about 25 g/L zinc, from about 2 to about 4 g/L magnesium, from 1 about to about ~10 g/L m~ng~nese and from about 190 to about 200 g/L sulfuric acid.
~ A line 85 is conn~octed at one end to premixer 30 and at the other end to an acid holding tank 90. If a sulfur-ammonium sulfate fertilizer is to be 30 produced, acid holding tank 90 contains sulfuric acid. If a sulfur-ammonium phosphate fertilizer is to be produced, acid holding tank 90 contains phosphoric acid. If a final product cont~inin~ both ammonium phosphate and CA 0221414~ 1997-08-28 W O96127S71 PCT/CAg6100129 arnmonium sulfate is desired, acid holding tank 90 contains sulfuric acid and phnsphnric acid. ~ltern~tively, acid holding tank 90 may be divided into two independent tanks (not shown), each independent tank cont~ining one of the acids and further comprising a line to feed each acid to premixer 30.
Mixer 15 is provided with an outlet 95 to which is conn~cte~ a thermost~ti~lly heated line 100. Line 100 is cnnn~cte~l to a granulation unit 110. Gram-l~tion unit 110 is not particularly le.,LIicL~d and suitable units areknown in the art. See, for example, United States patent 4,234,318 (~iggin~
et al.), the contents of which are hereby inco"~o.dted by .ere.~;-.ce.
From granulationunit 110 a stream comprising on-specificationproduct exits via a line 125 and is fed to dryer, screening and p~ ging units (not shown). Another stream colll~lisillg under-sized, off-specification product, also known as "fines" together with air used in granulation unit 110, exits granulation unit 110 via a line 145 and is fed to a scrubber unit 150. Aqueous scrubber liquor formed in scrubber unit 150 is fed to scruWer liquor holding tank 60 via a line 155. Cleaned air e,~ s from scrubber unit 150 via line 115 and is further treated and/or vented to the atmosphere.
The present sulfur-cont~ining fertilizer may be produced in the following manner. A suitable valve (not shown) in line 55 2~ cent holding tank 60 is opened and aqueous scrubber liquor begins to flow in line 55.
Suitable valves (not shown) in lines 65 and 75, respectively, are opened to permit a flow of ammonia and gramll~ti~n agent, ~ peclivt:ly. Preferably, flow in lines 55 and 65 is ~rei,~uli~ed, more preferably in the range of from about 200 to about 300 psi (about 1380 to about 2070 kPa), most preferably in the range of from about 250 to about 300 psi (about 1725 to about 2070 kPa).
Con~;u~ ly, a valve (not shown) in line 85 is opened to permit a flow of acid (sulfuric acid or phosphoric acid) to premixer 30. Preferably, the flow in line 85 is pressurized, more preferably in the range of from about 200 to about 300 psi (about 1380 to about 2070 kPa), most preferably in the range of from about 250 to about 300 psi (about 1725 to about 2070 kPa).
CA 0221414~ 1997-08-28 Thus, the contt~nt~ of line 55 at inlet 40 of quill 35 comprise ammonia, scrubber liquor and granulation agent. The aqueous liquid is then fed to quill 35 where it exits Lllclcrlvnl via jets 50 into the mass of acid present in premixer 30 to form an c~olhellllic reaction mi~lulc. As will be a~alclll to 5those of skill in the art, these flows may be reversed such that the aqueous liquid is fed in and around quill 35, and the acid (or acids) is added through quill 35. This alternative configuration has the added advantage of minimi7.in~
corrosion of quill 35 and jets 50.
The exother~nic reaction mixture is then fed from premixer 30 to mixer 15. Con;ullclllly, a valve (not shown) in line 20 is opened to permit a flow of molten sulfur to enter mixer 15. Preferably, the flow in line 20 is s~ul.~.ed, more preferably in the range of from about 200 to about 300 psi (about 1380 to about 2070 kPa), most preferably in the range of from about 250 to about 300 psi (about 1725 to about 2070 kPa). The exoth~rmir reaction mixture and molten sulfur stream are homogeni7.od in mixer 15 to produce a multi-component slurry. As t~ c--~se-l above, mixer 15 is conventional and the operation thereof to provide a pressure drop of at least about 200 kPa is within the purview of a person skilled in the art.
The multi-component slurry exits mixer 15 via outlet 95 and enters line 100. As tli~clls~ed above, a prcs~ulc drop is created across mixer 15.
Preferably, this results in the pressure of the multi-component slurry exiting mixer 15 being in the range of from about 10 to about 50 psi (about 70 to about 350 kPa), more preferably from about 10 to about 30 psi (about 70 to about 210 kPa).
Preferably, line 100 is m~int~in~d at a temperature of at least about 120~C, more preferably in the range of from about 130~ to about 170~C.
This may be accomplished by m~int~ining a back-plcs~ule in the sprayer (not shown) in granulation unit 110 sufficient to avoid steam flash of the multi-component slurry which would cause cooling of the slurry to a temperature below that which is desired to achieve good granulation.
Preferably, within about 10 seconds of exiting mixer 15, the multi-component slurry enters granulation unit 110 wherein it is solidified and wo 96127571 PCr/CA96100129 gr~mll~t~l. As ~ cllesed hereinabove, gr~mll~ti~ n unit 110 is conventional and the operation thereof to produce a gr~mll~te~ product is within the purview of a person skill in the art.
As rli~cll~d above, on-specification product is removed from the S effluent of granulation unit 110 by any conventional technique such as screening and, ~lc..,arlel, is conveyed drying, screening and pae~ging units (not shown). The air from granulation unit 110 contains fine dust particles and this stream is passed through scrubber unit 150. Aqueous scrubber liquor formed in scrubber unit 150 is fed to scrubber liquor holding tank 60 via a 10 line lSS and cleaned air e~ ;s from scrubber unit 150 via line llS.
As is known in the art, the amounts of ammonia, acid, sulfur and aqueous stream may be regulated according to the ~lo~cllies desired in the product. For example, the acid typically is used in an amount which regulates the rate of production of the sulfur-cont~ining fertilizer. The amount of 15 ammonia used is approximately stoichiometric to provide a sulfur-co~ g fertilizer having a pH of from about 4 to about 7.5. The aqueous stream (e.g.
scrubber liquor) is used in an amount to ensure s~ti~f~ctory soli~lifir~ti~ n ofthe homogenized melt, and also to help to control the mixer L~ elaLule. The molten sulfur is used in amount which will result in t'ne desired sulfur level in the fertilizer product.
While the present invention has been described in detail with l~Çelcl~ce to a single illustrated embodiment, it will of course be readily understood thata number of modifications to the illu7LIated embodiment will be ~ar~lll to those of skill in the art.
For example, granulation unit 110 may be modified or substituted with a dirr~lenl soli~lifir~tion unit. Another pl~f~ d solillifir~tic~n unit is a prilling tower, for example, such as those disclosed in United States patents 4,153,431 (Higgins) and 4,389,356 (Higgins), the contents of each of which are hereby incorporated by .-,rerellce. Other ~ rt:lled soli~lifir~tion units include an inrlin-od rotating pan and a flni-li7tod bed.
Another motliflr~tinn contemplated herein is elimin~tion from the illustrated embodiment of the need for a gr~nlll~tion agent. As is known in CA 0221414~ 1997-08-28 the art, granulation agents are desirable specifically for in ammonium sulfate production since, in granulation processes, this compound a&eres to itself relatively poorly. In the present process, while use of a gr~n~ tion agent is ~l~,r~lled is believed to be not required since the molten sulfur added during S the present process will serve to promote the needed a&esion. -Yet another modification contemplated herein is mo~lifi-~tion of the illustrated embodiment to utilize the granulation agent at any point in the process up to the soli-lifi~tion unit. In other words, it is contemplated that the granulation agent can be injected, for example, adjacent granulation unit 10 110 after mixer 15.
Yet another motlific~tion cont~mplated herein is elimin~tion from the illustrated embodiment of the need for a sclubbel liquor. Specif1cally, the use of a scrubber liquor is a col~venient way to introduce water into the reaction system. As is known in the art, water is needed to facilitate mixing of the 15 re~ct~nt~, and h~nllling and gr~n~ tion of the reaction product. In the present process, it is convenient, and thus ~l~rell~d, to use scrubber liquor as the water source since scluWillg and production of scrubber liquor is collv~llLionalin the art. However, it should be clearly recognized ~hat the source of water can be other than scrubber liquor. For example, the source of water could be 20 a dilute stream of acid. ~lt~rn~tively, the source of water could be the stripped zinc electrolyte, if used. Of course, persons skilled in the art will recognize that the source of water can be spread over two or more reactant streams to the process (e.g. portion in the form of relatively dilute acid and portion in the form of stripped zinc electrolyte).
Yet another mo~lifir~tion contemplated herein is modification to the illustrated embodiment of the combination of mixer 15 and premixer 30.
Specifically, it is contemplated that these elements need not be integral and can be remote from one another.
Yet another modifir~tion contemplated herein is elimin~tlod of j~k~oted mixer 15 shown in the illustrated emborlim~nt In this modification, the output of premixer 30 would be conn~qct~ directly to line 100 and line 20 from holding tank 25 would be conn~cte-l via a con\~llLional valve junction to W O 96/27S71 PCTICAg6100129 line 100. This mc~1ifir~tion eli...i..~s the need for j~cl~te(l mixer 15 and allows for in-line mixing of the molten sulfur with the reaction ~ n~
from premixer 30 (i.e. line 100 provides in situ mixing of the molten sulfur and the reaction Il~xlule). Such a design mo-lifir~tion was used in the J 5 Example described hereinbelow.
Further modifications will be appalelll to those of skill in the art with this specification in hand, which modifications do not depart from the spirit of the present invention.
Embo-limPnt~ of the present invention will be described with lcrclcllce to the following Example which should not be used to limit the scope of the mvenhon.
EXAMPLE
In this Example, a fertilizer cont~ining sulfur and ammonium sulfate was produced in a pilot plant.
The design of t'ne pilot plant reactor was similar to that disclosed in the Figure referred to above, modified in the following lllam~el. The flow into quill 35 and premixer 30 was leve.~,ed such that ammonia and water were fed to premixer 30 to ~ull~und quill 35 and sulfuric acid was fed into quill 35.
Further, mixer 15 was elimin~t~ and the output from premixer 30 was fed dhcclly to a heated line. The molten sulfur was injected into the heated line via an injection nozzle to provide in-line mixing of the molten sulfur stream with sulfuric acid/water/ammonia stream.
Ammonia vapour was fed from ammonia bottles via a plC~7.7UlC
regulator set at 70 psig and through a mass flowmeter/controller. Sulfur was fed from a steam jacketed, nitrogen plcs~,uli~ed tank at 90 psig via a steam j~ck~tecl line and steam j~rk~te~l rotameter to the injection nozzle.
Supplementary electric heaters were used to heat the sulfur line, as n~cess~y.
Large lab size gear pumps were used to pump sulfuric acid (82 psig) and water (80 psig) through their .e~,l,e.;li~e lines to the reactor (i.e. water to premixer and sulfuric acid to quill).
W O96/27S71 PCT/CAg6/00129 The reactor was opelaled for 90 ...i..~ s at 166~C. Spray slurry samples were periodically taken and found to contain 47% elem~ont~l sulfur.
Gr~mll~t~o~l samples from the gr~mll~tinn unit co~ ed 1040% sulfur, as the particles in the granulator were slowly changed from the fine ammonium 5 sulfate which was used as the initial dry feed for the granulator.
The gramll~te~l samples were subjected to a sulfur size distribution analysis by conventional wet screen analysis. The particle size distribution of the gr~mll~te~l product may be found in Table 1.
MeshParticle Size (~m) Fraction (wt. %) +48 297 1.9 +65 208 4.3 + 100 150 10.3 +200 75 27 +325 45 81 Thus, these test results illnstrat~ that approximately 75% of sulfur particles in the fertilizer had a particle size of less than 75 ~bm.
Claims (30)
1. A homogeneous granulated sulfur-containing fertilizer, each granule of the fertilizer comprising:
a uniform dispersion of (i) sulfur particles in (ii) a granule matrix comprising at least one member selected from the group consisting of ammonium sulfate, ammonium phosphate and mixtures thereof, wherein the sulfur particles in the uniform dispersion have an average particle size of about 100 µm or less when the granule of fertilizer is disintegrated.
-15-a What is claimed is:
a uniform dispersion of (i) sulfur particles in (ii) a granule matrix comprising at least one member selected from the group consisting of ammonium sulfate, ammonium phosphate and mixtures thereof, wherein the sulfur particles in the uniform dispersion have an average particle size of about 100 µm or less when the granule of fertilizer is disintegrated.
-15-a What is claimed is:
2. The fertilizer defined in claim 1, wherein the uniform dispersion comprises sulfur and ammonium sulfate.
3. The fertilizer defined in claim 1, wherein the uniform dispersion comprises sulfur and ammonium phosphate.
4. The fertilizer defined in claim 1, further comprising at least on trace element selected from the group consisting of zinc, magnesium, manganese, iron, copper, calcium and mixtures thereof, wherein the aggregate amount of trace element is less than about 5% by weight of the fertilizer.
5. The fertilizer defined in claim 1, further comprising up to about 1.5%
by weight zinc, from about 0.01% to about 0.2% by weight magnesium and from about 0.01% to abut 0.1% by weight manganese.
by weight zinc, from about 0.01% to about 0.2% by weight magnesium and from about 0.01% to abut 0.1% by weight manganese.
6. The fertilizer defined in claim 1, further comprising from abut 0.4%
to about 1.3% by weight zinc, from about 0.07% to about 0.16% by weight magnesium and from about 0.04% to about 0.09% by weight manganese.
to about 1.3% by weight zinc, from about 0.07% to about 0.16% by weight magnesium and from about 0.04% to about 0.09% by weight manganese.
7. A process for producing a granulated sulfur-containing fertilizer comprising the steps of:
(i) providing a first stream comprising ammonia;
(ii) providing a second stream comprising at least one member selected from the group consisting of sulfuric acid, phosphoric acid and mixtures thereof;
(iii) providing a third stream comprising an aqueous liquid;
(iv) mixing the first stream, the second stream and the third stream to form a liquid reaction mixture;
(v) feeding the liquid reaction mixture to a mixer;
(vi) feeding a fourth stream comprising molten sulfur to the mixer prior to solidification of the reaction mixture; and (vii) solidifying the homogenized melt to produce the granulated sulfur-containing fertilizer.
(i) providing a first stream comprising ammonia;
(ii) providing a second stream comprising at least one member selected from the group consisting of sulfuric acid, phosphoric acid and mixtures thereof;
(iii) providing a third stream comprising an aqueous liquid;
(iv) mixing the first stream, the second stream and the third stream to form a liquid reaction mixture;
(v) feeding the liquid reaction mixture to a mixer;
(vi) feeding a fourth stream comprising molten sulfur to the mixer prior to solidification of the reaction mixture; and (vii) solidifying the homogenized melt to produce the granulated sulfur-containing fertilizer.
8. The process defined in claim 7, wherein Step (vii) comprises feed the homogenized melt to a solidification unit.
9. The process defined in claim 8, wherein Step (vii) further comprises scrubbing dust laden air from the solidification unit to produce a scrubber liquor.
10. The process defined in claim 9, wherein the third stream comprises the scrubber liquor.
11. The process defined in claim 7, wherein the solidification unit is a granulation unit.
12. The process defined in claim 7, wherein the homogenized melt is maintained at a temperature of at least about 120°C up to the point at which it enters the solidification unit.
13. The process defined in claim 7, wherein the solidification unit is a prilling tower.
14. The process defined in claim 7, wherein the solidification unit is an inclined rotating pan.
15. The process defined in claim 7, wherein the solidification unit is a fluidized bed.
16. The process defined in claim 7, wherein Step (iv) comprises initially mixing the second stream and the third stream and thereafter adding the first stream.
17. The process defined in claim 7, wherein prior to Step (iv), a granulation agent is added to at least one of the first stream, the second stream and the third stream.
18. The process defined in claim 17, wherein the granulation agent is selected from the group consisting of zinc sulphate, ammonium phosphate, aluminum sulfate and mixtures thereof.
17a
17a
19. The process defined in claim 17, wherein the granulation agent is a stripped zinc electrolyte comprising from about 10 to about 30 g/L zinc, up to about 10 g/L magnesium, up to about 10 g/L manganese and up to about 250 g/L sulfuric acid.
20. The process defined in claim 17, wherein the granulation agent is a stripped zinc electrolyte comprising from about 20 to about 25 g/L zinc, from about 2 to about 4 g/L
magnesium, from about 1 to about 10 g/L manganese and from about 190 about 200 g/L
sulfuric acid.
magnesium, from about 1 to about 10 g/L manganese and from about 190 about 200 g/L
sulfuric acid.
21. The process defined in claim 7, wherein prior to Step (iv), a granulation agent is added to the first stream, the granulation agent being selected from the group consisting of zinc sulphate, ammonium phosphate, aluminum sulfate and mixtures thereof.
22. The process defined in claim 7, wherein prior to Step (iv), a granulation agent is added to the third stream, the granulation agent being selected from the group consisting of zinc sulphate, ammonium phosphate, aluminum sulfate and mixtures thereof.
23. The process defined in claim 7, wherein Step (iv) is conducted in a premixer and, in accordance with Step (v), the resulting liquid reaction mixture is fed to the mixer.
24. The process defined in claim 23, wherein the mixer is a pipe reactor equipped with an inlet for molten sulfur.
25. The process defined in claim 7, wherein Step (vi) further comprises maintaining a pressure drop across the mixer of at least about 200 kPa.
26. The process defined in claim 7, wherein Step (vi) further comprises maintaining a pressure drop across the mixer of at least about 350 kPa.
27. The process defined in claim 7, wherein Step (vii) comprises maintaining a pressure drop across the mixer of at least about 500 kPa.
28. The process defined in claim 7, wherein the fourth stream is maintained at a temperature of from about 130° to about 170°C.
29. The process defined in claim 7, wherein the fourth stream is maintained at a temperature of from about 135° to about 160°C.
30. The process defined in claim 7, wherein for production of a sample of the sulfur-containing fertilizer, the period between Step (vi) and Step (vii) isless than about 10 seconds.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/398,532 | 1995-03-06 | ||
| US08398532 US5571303B1 (en) | 1995-03-06 | 1995-03-06 | Sulfur-based fertilizer and process for production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2214145A1 true CA2214145A1 (en) | 1996-09-12 |
Family
ID=23575737
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002214145A Abandoned CA2214145A1 (en) | 1995-03-06 | 1996-03-04 | Sulfur-containing fertilizer and process for production thereof |
Country Status (15)
| Country | Link |
|---|---|
| US (1) | US5571303B1 (en) |
| EP (1) | EP0813509B1 (en) |
| JP (1) | JPH11502185A (en) |
| CN (1) | CN1072193C (en) |
| AT (1) | ATE181721T1 (en) |
| AU (1) | AU4780796A (en) |
| BR (1) | BR9607595A (en) |
| CA (1) | CA2214145A1 (en) |
| DE (1) | DE69603069T2 (en) |
| DK (1) | DK0813509T3 (en) |
| ES (1) | ES2135870T3 (en) |
| GR (1) | GR3031349T3 (en) |
| NO (1) | NO974024D0 (en) |
| NZ (1) | NZ302201A (en) |
| WO (1) | WO1996027571A1 (en) |
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| US6013209A (en) * | 1996-04-19 | 2000-01-11 | Airborne Industrial Minerals Inc. | Granulation method |
| US6132484A (en) * | 1998-04-17 | 2000-10-17 | Airborne Industrial Minerals Inc. | Wet granulation method for generating fertilizer granules |
| US6331193B1 (en) | 1998-04-17 | 2001-12-18 | Airborne Industrial Minerals Inc. | Wet granulation method generating sulfur granules |
| US6454979B1 (en) | 1998-04-17 | 2002-09-24 | Airborne Industrial Minerals Inc. | Wet granulation method for generating granules |
| US6582637B1 (en) | 1999-05-05 | 2003-06-24 | Agronomic Growth Industries Ltd. | Compost granulation method |
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| CA1144771A (en) * | 1980-12-24 | 1983-04-19 | Stewart G. Bexton | Manufacture of urea sulfur fertilizer |
| US4372872A (en) * | 1981-02-17 | 1983-02-08 | Union Oil Company Of California | Sulfur suspensions |
| CA1154213A (en) * | 1981-07-07 | 1983-09-27 | John T. Higgins | Sulfur prilling |
| US4589904A (en) * | 1984-09-25 | 1986-05-20 | Tennessee Valley Authority | Granulation of crystalline by-product ammonium sulfate |
| US5112379A (en) * | 1984-10-25 | 1992-05-12 | Union Oil Company Of California | Multicomponent soil supplement |
| IT1252664B (en) * | 1991-12-23 | 1995-06-21 | Enichem Agricoltura Spa | PROCESS FOR THE GRANULATION OF A FERTILIZER DENOMINATED AMMONIC NITRATE |
| US5383951A (en) * | 1993-08-27 | 1995-01-24 | Cominco Ltd. | Production of granular ammonium sulphate using stripped zinc electrolyte as a granulating aid |
-
1995
- 1995-03-06 US US08398532 patent/US5571303B1/en not_active Expired - Fee Related
-
1996
- 1996-03-04 DK DK96903848T patent/DK0813509T3/en active
- 1996-03-04 JP JP8526498A patent/JPH11502185A/en active Pending
- 1996-03-04 CA CA002214145A patent/CA2214145A1/en not_active Abandoned
- 1996-03-04 AT AT96903848T patent/ATE181721T1/en not_active IP Right Cessation
- 1996-03-04 CN CN96193527A patent/CN1072193C/en not_active Expired - Fee Related
- 1996-03-04 WO PCT/CA1996/000129 patent/WO1996027571A1/en active IP Right Grant
- 1996-03-04 DE DE69603069T patent/DE69603069T2/en not_active Expired - Fee Related
- 1996-03-04 BR BR9607595A patent/BR9607595A/en not_active IP Right Cessation
- 1996-03-04 ES ES96903848T patent/ES2135870T3/en not_active Expired - Lifetime
- 1996-03-04 EP EP96903848A patent/EP0813509B1/en not_active Expired - Lifetime
- 1996-03-04 AU AU47807/96A patent/AU4780796A/en not_active Abandoned
- 1996-03-04 NZ NZ302201A patent/NZ302201A/en unknown
-
1997
- 1997-09-02 NO NO974024A patent/NO974024D0/en not_active Application Discontinuation
-
1999
- 1999-09-29 GR GR990402442T patent/GR3031349T3/en unknown
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6013209A (en) * | 1996-04-19 | 2000-01-11 | Airborne Industrial Minerals Inc. | Granulation method |
| US6132484A (en) * | 1998-04-17 | 2000-10-17 | Airborne Industrial Minerals Inc. | Wet granulation method for generating fertilizer granules |
| US6331193B1 (en) | 1998-04-17 | 2001-12-18 | Airborne Industrial Minerals Inc. | Wet granulation method generating sulfur granules |
| US6454979B1 (en) | 1998-04-17 | 2002-09-24 | Airborne Industrial Minerals Inc. | Wet granulation method for generating granules |
| US6582637B1 (en) | 1999-05-05 | 2003-06-24 | Agronomic Growth Industries Ltd. | Compost granulation method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1072193C (en) | 2001-10-03 |
| EP0813509A1 (en) | 1997-12-29 |
| WO1996027571A1 (en) | 1996-09-12 |
| MX9706804A (en) | 1998-08-30 |
| DK0813509T3 (en) | 2000-01-31 |
| US5571303A (en) | 1996-11-05 |
| BR9607595A (en) | 1998-07-07 |
| NZ302201A (en) | 2000-01-28 |
| NO974024L (en) | 1997-09-02 |
| GR3031349T3 (en) | 2000-01-31 |
| CN1182411A (en) | 1998-05-20 |
| ATE181721T1 (en) | 1999-07-15 |
| JPH11502185A (en) | 1999-02-23 |
| DE69603069T2 (en) | 2000-03-09 |
| AU4780796A (en) | 1996-09-23 |
| EP0813509B1 (en) | 1999-06-30 |
| ES2135870T3 (en) | 1999-11-01 |
| NO974024D0 (en) | 1997-09-02 |
| DE69603069D1 (en) | 1999-08-05 |
| US5571303B1 (en) | 2000-10-17 |
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| EEER | Examination request | ||
| FZDE | Discontinued |